In a radio communication network, such as a mobile phone network, mobile stations monitor the quality of received signals and report the received signal quality back to a base station, typically in a control channel.
It has been proposed that a mobile station report received signal quality in a slow associated control channel (SACCH) using a three bit code. The signal quality is determined as the bit error rate (BER) of the received signal before channel decoding and is averaged over one SACCH multiframe, for example 480 ms.
The BER is only used if the a block is correctly received, i.e. it passes a CRC (cyclic redundancy code) check. If a block is not correctly received, a default notional BER of, for example 50%, is assumed.